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 * to you under the Apache License, Version 2.0 (the
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package org.apache.http.client.utils;

import java.net.URI;
import java.net.URISyntaxException;
import java.util.List;
import java.util.Locale;
import java.util.Stack;

import org.apache.http.HttpHost;
import org.apache.http.conn.routing.RouteInfo;
import org.apache.http.util.Args;
import org.apache.http.util.TextUtils;

A collection of utilities for URIs, to workaround bugs within the class or for ease-of-use features. 
Since:
4.0/**
 * A collection of utilities for {@link URI URIs}, to workaround
 * bugs within the class or for ease-of-use features.
 *
 * @since 4.0
 */
public class URIUtils {

     
Constructs a URI using all the parameters. This should be used instead of URI(String, String, String, int, String, String, String) or any of the other URI multi-argument URI constructors. 
Params:
scheme – 
           Scheme name
host – 
           Host name
port – 
           Port number
path – 
           Path
query – 
           Query
fragment – 
           Fragment
Throws:
URISyntaxException – 
            If both a scheme and a path are given but the path is
            relative, if the URI string constructed from the given
            components violates RFC 2396, or if the authority
            component of the string is present but cannot be parsed
            as a server-based authority
Deprecated:
(4.2) use URIBuilder./**
         * Constructs a {@link URI} using all the parameters. This should be
         * used instead of
         * {@link URI#URI(String, String, String, int, String, String, String)}
         * or any of the other URI multi-argument URI constructors.
         *
         * @param scheme
         *            Scheme name
         * @param host
         *            Host name
         * @param port
         *            Port number
         * @param path
         *            Path
         * @param query
         *            Query
         * @param fragment
         *            Fragment
         *
         * @throws URISyntaxException
         *             If both a scheme and a path are given but the path is
         *             relative, if the URI string constructed from the given
         *             components violates RFC&nbsp;2396, or if the authority
         *             component of the string is present but cannot be parsed
         *             as a server-based authority
         *
         * @deprecated (4.2) use {@link URIBuilder}.
         */
    @Deprecated
    public static URI createURI(
            final String scheme,
            final String host,
            final int port,
            final String path,
            final String query,
            final String fragment) throws URISyntaxException {
        final StringBuilder buffer = new StringBuilder();
        if (host != null) {
            if (scheme != null) {
                buffer.append(scheme);
                buffer.append("://");
            }
            buffer.append(host);
            if (port > 0) {
                buffer.append(':');
                buffer.append(port);
            }
        }
        if (path == null || !path.startsWith("/")) {
            buffer.append('/');
        }
        if (path != null) {
            buffer.append(path);
        }
        if (query != null) {
            buffer.append('?');
            buffer.append(query);
        }
        if (fragment != null) {
            buffer.append('#');
            buffer.append(fragment);
        }
        return new URI(buffer.toString());
    }

    
A convenience method for creating a new URI whose scheme, host and port are taken from the target host, but whose path, query and fragment are taken from the existing URI. The fragment is only used if dropFragment is false. The path is set to "/" if not explicitly specified. 
Params:
uri – 
           Contains the path, query and fragment to use.
target – 
           Contains the scheme, host and port to use.
dropFragment – 
           True if the fragment should not be copied.
Throws:
URISyntaxException – 
            If the resulting URI is invalid./**
     * A convenience method for creating a new {@link URI} whose scheme, host
     * and port are taken from the target host, but whose path, query and
     * fragment are taken from the existing URI. The fragment is only used if
     * dropFragment is false. The path is set to "/" if not explicitly specified.
     *
     * @param uri
     *            Contains the path, query and fragment to use.
     * @param target
     *            Contains the scheme, host and port to use.
     * @param dropFragment
     *            True if the fragment should not be copied.
     *
     * @throws URISyntaxException
     *             If the resulting URI is invalid.
     */
    public static URI rewriteURI(
            final URI uri,
            final HttpHost target,
            final boolean dropFragment) throws URISyntaxException {
        Args.notNull(uri, "URI");
        if (uri.isOpaque()) {
            return uri;
        }
        final URIBuilder uribuilder = new URIBuilder(uri);
        if (target != null) {
            uribuilder.setScheme(target.getSchemeName());
            uribuilder.setHost(target.getHostName());
            uribuilder.setPort(target.getPort());
        } else {
            uribuilder.setScheme(null);
            uribuilder.setHost(null);
            uribuilder.setPort(-1);
        }
        if (dropFragment) {
            uribuilder.setFragment(null);
        }
        final String path = uribuilder.getPath();
        if (TextUtils.isEmpty(path)) {
            uribuilder.setPath("/");
        } else {
            final StringBuilder buf = new StringBuilder(path.length());
            boolean foundSlash = false;
            for (int i = 0; i < path.length(); i++) {
                final char ch = path.charAt(i);
                if (ch != '/' || !foundSlash) {
                    buf.append(ch);
                }
                foundSlash = ch == '/';
            }
            uribuilder.setPath(buf.toString());
        }
        return uribuilder.build();
    }

    
A convenience method for rewriteURI(URI, HttpHost, boolean) that always keeps the fragment. /**
     * A convenience method for
     * {@link URIUtils#rewriteURI(URI, HttpHost, boolean)} that always keeps the
     * fragment.
     */
    public static URI rewriteURI(
            final URI uri,
            final HttpHost target) throws URISyntaxException {
        return rewriteURI(uri, target, false);
    }

    
A convenience method that creates a new URI whose scheme, host, port, path, query are taken from the existing URI, dropping any fragment or user-information. The path is set to "/" if not explicitly specified. The existing URI is returned unmodified if it has no fragment or user-information and has a path. 
Params:
uri – 
           original URI.
Throws:
URISyntaxException – 
            If the resulting URI is invalid./**
     * A convenience method that creates a new {@link URI} whose scheme, host, port, path,
     * query are taken from the existing URI, dropping any fragment or user-information.
     * The path is set to "/" if not explicitly specified. The existing URI is returned
     * unmodified if it has no fragment or user-information and has a path.
     *
     * @param uri
     *            original URI.
     * @throws URISyntaxException
     *             If the resulting URI is invalid.
     */
    public static URI rewriteURI(final URI uri) throws URISyntaxException {
        Args.notNull(uri, "URI");
        if (uri.isOpaque()) {
            return uri;
        }
        final URIBuilder uribuilder = new URIBuilder(uri);
        if (uribuilder.getUserInfo() != null) {
            uribuilder.setUserInfo(null);
        }
        if (TextUtils.isEmpty(uribuilder.getPath())) {
            uribuilder.setPath("/");
        }
        if (uribuilder.getHost() != null) {
            uribuilder.setHost(uribuilder.getHost().toLowerCase(Locale.ROOT));
        }
        uribuilder.setFragment(null);
        return uribuilder.build();
    }

    
A convenience method that optionally converts the original URI either to a relative or an absolute form as required by the specified route. 
Params:
uri – 
           original URI.
Throws:
URISyntaxException – 
            If the resulting URI is invalid.
Since:
4.4/**
     * A convenience method that optionally converts the original {@link java.net.URI} either
     * to a relative or an absolute form as required by the specified route.
     *
     * @param uri
     *            original URI.
     * @throws URISyntaxException
     *             If the resulting URI is invalid.
     *
     * @since 4.4
     */
    public static URI rewriteURIForRoute(final URI uri, final RouteInfo route) throws URISyntaxException {
        if (uri == null) {
            return null;
        }
        if (route.getProxyHost() != null && !route.isTunnelled()) {
            // Make sure the request URI is absolute
            return uri.isAbsolute()
                            ? rewriteURI(uri)
                            : rewriteURI(uri, route.getTargetHost(), true);
        }
        // Make sure the request URI is relative
        return uri.isAbsolute() ? rewriteURI(uri, null, true) : rewriteURI(uri);
    }

    
Resolves a URI reference against a base URI. Work-around for bug in
java.net.URI (http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=4708535)
Params:
baseURI – the base URI
reference – the URI reference
Returns:
the resulting URI/**
     * Resolves a URI reference against a base URI. Work-around for bug in
     * java.net.URI (http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=4708535)
     *
     * @param baseURI the base URI
     * @param reference the URI reference
     * @return the resulting URI
     */
    public static URI resolve(final URI baseURI, final String reference) {
        return resolve(baseURI, URI.create(reference));
    }

    
Resolves a URI reference against a base URI. Work-around for bugs in
java.net.URI (e.g. http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=4708535)
Params:
baseURI – the base URI
reference – the URI reference
Returns:
the resulting URI/**
     * Resolves a URI reference against a base URI. Work-around for bugs in
     * java.net.URI (e.g. http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=4708535)
     *
     * @param baseURI the base URI
     * @param reference the URI reference
     * @return the resulting URI
     */
    public static URI resolve(final URI baseURI, final URI reference){
        Args.notNull(baseURI, "Base URI");
        Args.notNull(reference, "Reference URI");
        final String s = reference.toASCIIString();
        if (s.startsWith("?")) {
            String baseUri = baseURI.toASCIIString();
            final int i = baseUri.indexOf('?');
            baseUri = i > -1 ? baseUri.substring(0, i) : baseUri;
            return URI.create(baseUri + s);
        }
        final boolean emptyReference = s.isEmpty();
        URI resolved;
        if (emptyReference) {
            resolved = baseURI.resolve(URI.create("#"));
            final String resolvedString = resolved.toASCIIString();
            resolved = URI.create(resolvedString.substring(0, resolvedString.indexOf('#')));
        } else {
            resolved = baseURI.resolve(reference);
        }
        try {
            return normalizeSyntax(resolved);
        } catch (final URISyntaxException ex) {
            throw new IllegalArgumentException(ex);
        }
    }

    
Removes dot segments according to RFC 3986, section 5.2.4 and
Syntax-Based Normalization according to RFC 3986, section 6.2.2.
Params:
uri – the original URI
Returns:
the URI without dot segments/**
     * Removes dot segments according to RFC 3986, section 5.2.4 and
     * Syntax-Based Normalization according to RFC 3986, section 6.2.2.
     *
     * @param uri the original URI
     * @return the URI without dot segments
     */
    static URI normalizeSyntax(final URI uri) throws URISyntaxException {
        if (uri.isOpaque() || uri.getAuthority() == null) {
            // opaque and file: URIs
            return uri;
        }
        Args.check(uri.isAbsolute(), "Base URI must be absolute");
        final URIBuilder builder = new URIBuilder(uri);
        final String path = builder.getPath();
        if (path != null && !path.equals("/")) {
            final String[] inputSegments = path.split("/");
            final Stack<String> outputSegments = new Stack<String>();
            for (final String inputSegment : inputSegments) {
                if ((inputSegment.isEmpty()) || (".".equals(inputSegment))) {
                    // Do nothing
                } else if ("..".equals(inputSegment)) {
                    if (!outputSegments.isEmpty()) {
                        outputSegments.pop();
                    }
                } else {
                    outputSegments.push(inputSegment);
                }
            }
            final StringBuilder outputBuffer = new StringBuilder();
            for (final String outputSegment : outputSegments) {
                outputBuffer.append('/').append(outputSegment);
            }
            if (path.lastIndexOf('/') == path.length() - 1) {
                // path.endsWith("/") || path.equals("")
                outputBuffer.append('/');
            }
            builder.setPath(outputBuffer.toString());
        }
        if (builder.getScheme() != null) {
            builder.setScheme(builder.getScheme().toLowerCase(Locale.ROOT));
        }
        if (builder.getHost() != null) {
            builder.setHost(builder.getHost().toLowerCase(Locale.ROOT));
        }
        return builder.build();
    }

    
Extracts target host from the given URI. 
Params:
uri – 
Returns:
the target host if the URI is absolute or null if the URI is relative or does not contain a valid host name.
Since:
4.1/**
     * Extracts target host from the given {@link URI}.
     *
     * @param uri
     * @return the target host if the URI is absolute or {@code null} if the URI is
     * relative or does not contain a valid host name.
     *
     * @since 4.1
     */
    public static HttpHost extractHost(final URI uri) {
        if (uri == null) {
            return null;
        }
        HttpHost target = null;
        if (uri.isAbsolute()) {
            int port = uri.getPort(); // may be overridden later
            String host = uri.getHost();
            if (host == null) { // normal parse failed; let's do it ourselves
                // authority does not seem to care about the valid character-set for host names
                host = uri.getAuthority();
                if (host != null) {
                    // Strip off any leading user credentials
                    final int at = host.indexOf('@');
                    if (at >= 0) {
                        if (host.length() > at+1 ) {
                            host = host.substring(at+1);
                        } else {
                            host = null; // @ on its own
                        }
                    }
                    // Extract the port suffix, if present
                    if (host != null) {
                        final int colon = host.indexOf(':');
                        if (colon >= 0) {
                            final int pos = colon + 1;
                            int len = 0;
                            for (int i = pos; i < host.length(); i++) {
                                if (Character.isDigit(host.charAt(i))) {
                                    len++;
                                } else {
                                    break;
                                }
                            }
                            if (len > 0) {
                                try {
                                    port = Integer.parseInt(host.substring(pos, pos + len));
                                } catch (final NumberFormatException ex) {
                                }
                            }
                            host = host.substring(0, colon);
                        }
                    }
                }
            }
            final String scheme = uri.getScheme();
            if (!TextUtils.isBlank(host)) {
                try {
                    target = new HttpHost(host, port, scheme);
                } catch (final IllegalArgumentException ignore) {
                }
            }
        }
        return target;
    }

    
Derives the interpreted (absolute) URI that was used to generate the last request. This is done by extracting the request-uri and target origin for the last request and scanning all the redirect locations for the last fragment identifier, then combining the result into a URI. 
Params:
originalURI – 
           original request before any redirects
target –  if the last URI is relative, it is resolved against this target, or null if not available.
redirects –  collection of redirect locations since the original request or null if not available.
Returns:
interpreted (absolute) URI/**
     * Derives the interpreted (absolute) URI that was used to generate the last
     * request. This is done by extracting the request-uri and target origin for
     * the last request and scanning all the redirect locations for the last
     * fragment identifier, then combining the result into a {@link URI}.
     *
     * @param originalURI
     *            original request before any redirects
     * @param target
     *            if the last URI is relative, it is resolved against this target,
     *            or {@code null} if not available.
     * @param redirects
     *            collection of redirect locations since the original request
     *            or {@code null} if not available.
     * @return interpreted (absolute) URI
     */
    public static URI resolve(
            final URI originalURI,
            final HttpHost target,
            final List<URI> redirects) throws URISyntaxException {
        Args.notNull(originalURI, "Request URI");
        final URIBuilder uribuilder;
        if (redirects == null || redirects.isEmpty()) {
            uribuilder = new URIBuilder(originalURI);
        } else {
            uribuilder = new URIBuilder(redirects.get(redirects.size() - 1));
            String frag = uribuilder.getFragment();
            // read interpreted fragment identifier from redirect locations
            for (int i = redirects.size() - 1; frag == null && i >= 0; i--) {
                frag = redirects.get(i).getFragment();
            }
            uribuilder.setFragment(frag);
        }
        // read interpreted fragment identifier from original request
        if (uribuilder.getFragment() == null) {
            uribuilder.setFragment(originalURI.getFragment());
        }
        // last target origin
        if (target != null && !uribuilder.isAbsolute()) {
            uribuilder.setScheme(target.getSchemeName());
            uribuilder.setHost(target.getHostName());
            uribuilder.setPort(target.getPort());
        }
        return uribuilder.build();
    }

    
This class should not be instantiated.
/**
     * This class should not be instantiated.
     */
    private URIUtils() {
    }

}